Liner for tube mills



7 June 14, 192 7.

LINDHARD LINER FOR TUBE MILLS Filed Oct. 1, 1926 Patented June 1 4, 1927.

UNITED] STATES PA EN orrlcs,

POVL '1. LIHDHABD, OF NEW YORK, ASSIONOB TO, I. L. SMIDTB NEW YORK, I. Y., A CORPORATION 01 NEW JERSEY;

'nnsmnronmnmasl' Application flied October 1,

In another application of the present aplicant for Letters Patent of the United tates, Serial No. 12,868 filed July 11,

1925, there is described an'improvement in liners for tube mills, etc., in accordance with which .the liner is made up .of longitudinal bars of metal with rounded working faces,

intervening spaces, bridge pieces connecting the bars at intervals and a filling of, cement. grout between the bars, the purpose being to secure greater efiiciency and endurance m at operation as compared with the cast metal vreduced cost, as compared with the silex capacity liners sometimes employed and of greatly liners. Long continued use of liners. constructed as described in that a plication has shown that they have great e ciency for a long period of use, giving a production capacity of seventy-five barrels .ofcement per hour, as compared with a production ofv about forty=five barrels per hour of mills lined with the best cast metal liners, but have not the endurance desired, the working surface, properly corrugated at the outset, becoming smooth, so that the efiiciency falls off greatly, while yet there remains a substantial. thickness of the liner which must be taken out and replaced bya new liner. It will be understood that continued efliciency of a mill' equipped with the liner, under'normal conditions of operation,

depends u n the maintenance of a corrugated ace which, in the rotatiom of the mill, will cause the to raised to the proper height so that grinding action shall be maintained as they tumble down the ascending side of the 'mill, and that,'for continued efliciency, the corrugated working surface should be maintained un-' til the liner is worn so thin that its replacement involves a umof waste. Inthe the liner described in that with, a relatively softer material, .such as cement 'grOuLinorderthatsuchfiIhng might wear away in proportion to the wearing th themetalbamalgthecorrugation of e worhng' surface thereby maintained. It was tlumght-to be desirable to a: to the PM! betwem the awidthasgreatasormewhatgreabr thafithemimmumof. ingbodiee,sud1aathed|ort adjacent bars and preferably u approximately but not 1926. Serial K0. 188,848. 7

bodies known as cyl ebs, and as little as or somewhat less than 518 maximum dimension of such bodies. A liner so constructed was found to give satisfactor results for a time, but became so smooth t at the capacit of the mill fell off materially before theiner was worn out. Continued investigation has shown that when the spaces between the bars, in the direction of rotation of the mill, are as narrow and are shaped as shown in the drawings ofthat application, the grind-- ing bodies themselves pack into such spaces, when the cement filling is worn out, and re main there, thus causing the liner to lose its corrugated working surface and to present a, comparatively smooth working surface, such t at the ca acity of the mill falls off considerably. Sudh continued investigation has also resulted in the developmentof theresent invention, in accordancewith whic it has been determined that the continued efficiency of the liner is dependent upon the angle between the lateral faces of tion between that angle and t of friction between the grinding bodies and the'lateral faces ofthe bars, the angle and the relation between the angle and the coeflicient of friction being such' that there shall be no tendency of the grinding bodies to pack and remain in the-spaces between the bars. It has been found that the best results are secured when the anglebetween v 'the adjacent working faces ofthe bars is less than thirty degrees tangent of one-half of the angle substantially equal to or larger the coeflicient of frictlonbe twe'en.-the bodies and the bars. The me of cementgrout as a backing-to securethe metallinerblochsinplaceisdesirable but its use as a bare is. unn. Incidentally, also, a meanshas been devlsedfor ening the liner blocks in the bridge pieces at the ends of .the longitudinal Between the bars,

and such that the with a subsequent reduction of to crackingatsuch pointx.

Theinventionwillbe fullyhereinafitgwithrefeehlilgtotheaccan ymg w1ngs,m

Fig l lielisafaceviewofplinerblock, pluralityofspaeedbarscast explained more fillingbetweenthe block andtheinvention.

4 the grinding Figure 2 is a view of the same in longitudinal section on the irregular plane indicated by the broken line 2-2 of Figure'l.

Figure 3 is a transverse section on the plane indicated by the broken line 3-3 of Figure 1. Y

Figure 4 is atransverse section showing several blocks or bars applied to the shell of the mill with a backing of cement grout to hold the blocks in place.

Figure 5 is a face view showing the placing of the blocks in a mill so asto break joints.

Figure 6 is a view in transverse section, on a larger scale than that of Figure 4:, illustrating the manner of coaction of cylindrical grinding bodies with the improved liner.

Longitudinal bars a, a, of a length convenient for handling and preferably having a rounded working surface a and a recessed rear surface a are united by casting in a block for convenience in handling and in application to the shell of the mill, with a suitable curvature of the block, the bars being separated from each other by longitudinal spaces, which preferably penetrate the block from face to back and are transverse to the direction of movement of the grinding bodies. The bars are preferably united at intervalsby bridge pieces 0 which, as shown in Figure 2, preferably do not extend to the working face of the block; but leave, in the front portion of the block, channels which extend continuously from end to end. Each outer bar of the block is preferably formed at its outer side with spacing projections 72, so as to provide spaces between the adjacent bars of .adjacent blocks.

In order that the bars or the blocks ofbars may be conveniently secured in the shell of the mill, cement grout f is used as a backing, filling the channels at the rear face or back of theblock'and perhaps entering to some extent into the spaces 1) between the lateral faces of the bars and thereby further assisting in securing the metal liner in place.

In order that the blocks may be strengthened at their ends and the possibility of cracking through the bridge pieces a at the ends may be reduced, tinned bars of iron 2',

transverse tothelongitudinal axis, areset into the mold in which the blocks are cast and the blocks are cast upon them.

The spaees 6 between the lateral faces of the bars are *given such width as to receive freely the grinding bodies 9 and are-so formed that there will be no tendency of bodies to pack and lodge therein during the operation of the mill. It has been found desirable that the angle between the lateral faces of the bars ,should be no longitudinal bars .of metal spaced "than the coefficient of manure less than about thirty degrees and that in any case it should be substantially equal to larger than the coefficient of friction between the grinding bodies and the material of which the bars are formed. When this angular relation is observed, it will be found that the corrugation of the working surface of the liner Will be maintained until the bars are worn to such a thinness that they become liable to breakageand to require replacement.

I claim as my invention:

1. A liner for tube mills, etc., vhaving longitudinal bars of metal spaced apart transversely to the direction of movement of the grinding bodies and having the lateral faces of adjacent bars formed in planes at anangleto each other so that the tangent of one-half of .such angle shall not be substantially less than the coeilicient of friction between the grinding bodies and the material of 'which the bars are formed, whereby the packing and lodging of the grinding bodies in thespaces between the bars is prevented and the corrugation of the working surface of the liner is maintained.

2. A liner for tube mills, etc. having apart transversely to the direction of movement of the grinding bodies and having the lateral faces of ad acent bars formed in planes at an angle to each other of not substantially less than thirty degrees, whereby the pack ing and lodging of the grinding bodiesin the spaces between the bars is prevented and the corrugation of the working surface of the liner is maintained.

3. A liner for tube mills, etc. comprising blocks of longitudinal bars of metal with intervening spaces and connecting bridge pieces, the bars having the lateral faces of adjacent bars formed in planes at an angle to each other so that thetangent of one-half of such angle shall not friction between the grinding bodies and the material of which the bars are formed, whereby the packing and lodging of the grinding bodies in the spaces between the bars is prevented and .the

corrugation of the working surface of the liner is maintained. v

4. A liner for tube mills, etc. comprising blocks of longitudinal bars of cast metal with interveningspaces and connecting bridge pieces and transverse rods of metal upon which the block is cast through the bridge pieces at the ends of the bars to be substantially less v strengthen the blocks and reduce the liability .to cracking.

This specification signed, this 30th da of Sept, A. n. 1926.

' P V I D ARD, 

